Doped solid oxide fuel cell electrolytes produced via combination of suspension plasma spray and very low pressure plasma spray.

Abstract

Solid oxide fuel cells (SOFCs) are a promising element of comprehensive energy portfolio due to their direct mechanism for converting the oxidization of fuel, such as hydrogen, into electrical energy. Plasma spray allows deposition of high melting temperature SOFC feedstock on complex surfaces, such as in non-planar SOFC designs. Dense, thin electrolytes of ideal composition for SOFCs can be created by suspension plasma spraying in a very low pressure environment. Compositional control is achieved with dissolved dopant compounds that are incorporated into the coating during spraying. In the work reported, sub-micron 8 mole% Y 2 O 3 -ZrO 2 (YSZ) powders, in suspension with scandium-nitrate dopants, were sprayed on NiO-YSZ anodes, at Sandia National Laboratories' Thermal Spray Research Laboratory. The spray chamber was held at 2.4-10 Torr, with the plasma composed of argon, hydrogen, and helium. The resultant electrolytes were 2-10 microns thick. Electrolyte microstructure and performance as part of a SOFC system is reported.

Very Low Pressure Plasma Spray—A Review of an Emerging Technology in the Thermal Spray Community

“…Successful operation has been demonstrated with liquid suspension, liquid precursors, and gaseous feedstocks. Sandia National Laboratories in collaboration with Purdue University has successfully deposited VLPPS coatings with a suspension feedstock delivery of Yttria Stabilized Zirconia particles suspended in ethanol [19]. Coating preparation from liquid precursors that chemically react in the plasma to form a coating have also been demonstrated.…”

“…Plasma spray technologies are already in use for solid oxide fuel cell (SOFC) preparation, but VLPPS has the potential for dramatic improvement over traditional plasma spray [9,15,[19][20][21][22][23][24][25]. Firstly, the VLPPS system provides dynamic control over the ambient chamber pressure during processing.…”

“…Thus, entire fuel cell systems can be constructed with measured or graded porosities to optimize each component in the cell [20][21][22][23]25]. In addition, the VLPPS process's ability to create thin and dense coatings makes it better suited than traditional thermal spray processes towards meeting the design criteria for SOFC electrolytes [9,15,19,20,22]. Furthermore, the columnar structure offers the potential for shorter ion diffusion paths through the electrolyte compared to a lamellar structure.…”